Data-Over-Cable Service Interface Specifications (“DOCSIS”) has been established by cable television network operators to facilitate transporting data traffic, primarily internet traffic, over existing community antenna television (“CATV”) networks. In addition to transporting data traffic as well as television content signals over a CATV network, multiple services operators (“MSO”) also use their CATV network infrastructure for carrying voice, video on demand (“VoD”) and video conferencing traffic signals, among other types.
An MSO may use what is known in the art as PacketCable for providing telephony services to users. PacketCable™, which is a trademark of CableLabs®, facilitates the presentation of a transparent interface to a user with respect to operation of the network. In other words, a user plugs a standard telephone into a user device, which presents to the telephone what appears to be a traditional plain old telephony service (“POTS”) line card interface. However, the user device transforms analog POTS signals to and from the telephone from/to internet packets.
Such a user device typically includes a media terminal adaptor (“MTA”) that performs processing of signals between the telephone and the network interface portions of the user device. When a user device, such as one containing an MTA, performs processing of telephony signals for transport over a network according to PacketCable, for example, signals from the MSO's network are typically attenuated for various reasons, including echo reduction, level equalization, interference with other device, etc.
However, each network is different, and different network operators may use equipment made by different vendors, thus making the desirable amount of attenuation at a given point in the network different from other points. One of the points that loss is induced is at the MTA user device. Accordingly, even when the equipment is identical, as may be the case when similar equipment is used in different countries, for example, the attenuation at one MTA user device may be different than at another identical MTA user device.
Although the difference between networks generally results in optimum performance with respect to signals received from the operators' networks, such as voice signals, other signals that may be generated at the MTA user device may not be provided to a telephone that is connected to the MTA user device at an optimum level.
This is because while the attenuation induced in the line interface portion of the MTA user device is determined based on optimizing the signal levels of network signals, other signals, such as call progress signal, are generally generated at a standard level that is not based on the actual line interface receive (“Rx”) attenuation used in a given MTA device. Thus, although the voice signals received at a telephone may be acceptable to the user, other signals levels, including dial tone, call ring back, busy signal, may be too loud or soft in comparison to the actual voice signal. Therefore, merely adjusting the volume level on the telephone would not be an acceptable solution because if it is adjusted to provide desirable dial tone signal level, the actual voice signal received from a caller on the other end of a telephone call may be too soft or too loud. Moreover, certain features, such as, for example, caller ID and dial-up modem signaling, which signals are produced in the MTA device, may not operate properly if the induced attenuation is to great.
Accordingly, there is a need in the art for a method and system for adjusting the signal level of call progress signals to compensate for the amount the induced attenuation deviates from a nominal value.